1. Field of Invention
The present invention relates to the squeeze film damper to be used as a rolling element bearing support.
2. Prior Knowledge
The damping effect of the squeeze film is well known. In the past, the squeeze film was not covered or covered by ring type seals to allow the radial movements of the rolling element bearings. It has the following disadvantages:
a) It does not have stiffness within the clearance of the squeeze film, unless an extra structure is added. PA1 b) It can not be used if the damping fluid is required to be separated from its environment. PA1 c) The damping fluid is supplied with high pressure and is spilled out of the damper. The fluid is not always present, i.e. the damper has a risk of damping fluid starvation especially during startup, acceleration, and shutdown. Without the fluid, the damper does not function.
U.S. Pat. No. 421,089 used squeeze film in the journal bearing as early as 1890. U.S. Pat. No. 2,631,901 used a combined viscose and squeeze film damping device in 1953. U.S. Pat. No. 4,781,1077 is an intershaft squeeze film damper designed in 1988. In none of above patents, a device is included in the design which may control the spill out of the damping fluid.
U.S. Pat. No. 4,134,309 is a flexible support of the rolling element bearings with an O-ring on one side and a fluid filled annular reservoir on the opposite side designed in 1979. U.S. Pat. No. 4,213,661 used end seals, such as piston ring type seals, to prevent the escape of fluid from the damper in 1980. U.S. Pat. No. 3,415,470 of 1968 is a fluid filled mounting system, not a system for a rolling element bearing support and does not use squeeze film. In other bearing support designs, U.S. Pat. No. 5,211,489 is a radial spline assembly to provide stiffness and damping designed in 1993.
No squeeze film damper is known, however, that is covered by torus shells, so that the torus shells provide stiffness within the clearance of squeeze film, separate damping fluid from its environment, and provide a damping fluid reservoir.